Rick, not a pissing match, I worked closely with Civil Engineers and Structural Engineers for decades. respect both, but the 2 don't necessarily cross over in my experience. most of my Projects were between 30 and 60 million dollars and would have 150 to 200 workmen involved and I had to be well versed in what they could and could not do, so I did my homework. and yes, you never cut the flanges. there are bending forces and shear.
I don't recall saying it was ok to cut a flange in my post.
You indeed didn't say that and I was agreeing with what you wrote. I was just using that to highlight the importance of the flanges in the strength of the beam to support the comment I thought, probably mistakenly, you were challenging.
By the way, structures is one branch of civil engineering, and structural engineers are therefore civil engineers. It is certainly true that not all civil engineers are qualified to be structural engineers in practice, and it's also certainly true that many engineers shouldn't be allowed to hold a tool in their hands or venture out into the real world without a guardian. (Those kinds of engineers don't, I suspect, end up on the Hobby Machinist forum, where people need enough sense not to hurt themselves.) But all civil engineers will have had more coursework in structures, by far, than they did in my line of expertise, which is also part of civil engineering. I had to go to grad school for that. Simple beams of various shapes with uniform and point loads doesn't get past sophomore-level statics and mechanics of materials and junior-level structures, let alone into concrete and steel structures classes plus a lot more.
Story time: When I took the second of two engineering examinations leading to getting licensed (and this was, oh, 44 years ago), I had the option in those days of specifying a specialty area within civil engineering on which I would be tested. I, like all my mates, chose structural engineering because my coursework prepared me much more thoroughly for the test, and the principles were much more deterministic and well-documented. If I'd chosen my own practice area, it would have been full of opinions and questionable methodologies based on crappy statistics and obsolete data. I went, totally by accident, to perhaps what was at the time the premiere university in the world for my specialty that taught well beyond traditional methods, and I didn't want to have answer questions incorrectly to get them "right". (I now do that every two years when I take my continuing education for renewing my registrations, so I'm not guessing. Speaking of which, Michigan is due this month. Sigh.) But the structures version of the test included a few reinforced concrete problems, a few steel problems, a few fastener problems, a few general statics problems, and a few general civil problems, all of which could be answered from memory or out of the ACI Concrete Handbook, the AISC Steel Manual, and the like. And now I've dated myself, ha! The PE exams are certainly not like that now.
Rick "did spend a lot of time with pavement and bridge designs" Denney
Obviously, that installation only loads the channel in bending for a foot between welds, and the main strength in bending comes from the steel beam. Similarly, a Unistrut trolley like mine loads the Unistrut in bending for two feet, but gets its main strength from the trusses. Both depend on the formed U-shape to support the trolley wheels without spreading or unfolding.